As is generally recognized by those of ordinary skill in the art, hydraulic pumps and motors of the gear type have found widespread use in heavy equipment and in various other implements wherein loads several times larger than were contemplated only a few years ago are involved. Obviously, this leads to much larger stresses being imposed on vital parts in the pump or motor which in turn increases the possibility of failure of an overloaded part. Usually when a failure occurs under conditions of actual use, it occurs with little warning so that a major breakdown of the equipment may occur when the equipment is in the field and repair parts and facilities are unavailable. It is recognized in the design of conventional gear pumps and motors that the severe load imposed on the bearings because of the substantial pressure differential which exists between the inlet and the outlet side when a pump or motor is under load is a frequent cause of failure. In modern hydraulic equipment a pressure differential of several thousand p.s.i. may exist across the gears. In a conventional gear pump, this pressure differential forces the gears and the side sealing plates against the interior wall portions of the housing on the inlet side, that is, the low pressure side of the gears. In fact, it has become accepted practice in the manufacture of gear pumps and motors to design the parts with the expectation that during the course of a break-in period, the housing wall on the low pressure side of the gears is gradually machined by a cutting and wearing action of the gear teeth to a matching configuration. As described in our copending application, sometimes the action of the teeth as cutters causes a tearing out of pieces of the housing at points where minor imperfections in the casting are present causing a destruction of the pump. Even if the pump housing is not damaged during break-in, as the pump is used, the machined region of the housing will continue to be gradually worn away. The inevitable result is a progressive loss in efficiency due to a less perfect seal between the teeth and housing interior, or a failure of some critical part. Should the bearings fail, the gear teeth cut into the housing thereby generating a large amount of contamination and the probable destruction of the pump. Although these problems can be alleviated by careful manufacturing and inspection procedures, and by selection of proper materials and the use of ample safety factors, the problems described constitute an inherent limitation to presently existing designs.